Multi-frequency antenna duplexer

ABSTRACT

A small-size multi-frequency antenna duplexer using surface acoustic wave filters and capable of dealing with a plurality of frequencies. Each antenna duplexer comprises two surface acoustic wave (SAW) filters used for transmission and reception, respectively, and having different frequency pass bands; a phase substrate; and a package housing the foregoing filters and substrate. The pass bands of the antenna duplexers are different from one another. This multi-frequency antenna duplexer comprises a plurality of antenna duplexers. A respective package ( 14 ) contains a transmitting surface acoustic wave filter ( 11   a   , 11   b ), a receiving surface acoustic wave filter ( 12   a   , 12   b ) and a phase substrate ( 13   a   , 13   b ). In this way, the size of multi-frequency antenna duplexer can be reduced.

TECHNICAL FIELD

[0001] The present invention relates to an antenna duplexer used inmobile communication appliances, and more particularly to amulti-frequency antenna duplexer.

BACKGROUND ART

[0002] A conventional antenna duplexer is generally formed of coaxialresonators or distributed constant type resonators, and the number ofstages of resonators and their shape are determined in order to obtaindesired electric characteristics such as passing band width andattenuation amount.

[0003] A conventional multi-frequency antenna duplexer includes, asshown in FIG. 13, plural antenna duplexers, that is, transmitter filters25 a, 25 b and receiver filters 26 a, 26 b respectivelly formed ofcoaxial resonators on a substrate 24. A switchable time divisionmultiple access (TDMA) system contains, as shown in FIG. 14, a branchingfilter 23 for branching the passing frequency, and single pole doublethrow (SPDT) switches 27 a, 27 b for changing over transmission andreception. The SPDT switches 27 a, 27 b respectively change overtransmitter terminals 16 c, 16 d, and receiver terminals 17 c, 17 d.

[0004] In this multi-frequency antenna duplexer, it is hard to reduce insize because the filter characteristic depends largely on the shape ofresonators. In particular, a non-switchable code division multipleaccess (CDMA) system requires multiple resonators, and is increased insize. For example, when an multi-frequency antenna duplexer largelydifferent in passing band frequency such as 800 MHz and 1.8 GHz iscomposed of distributed constant type resonators, the electriccharacteristic of substrate materials used in the distributed constanttype resonators depends on the frequency. Therefore, it is hard tooptimize the electric characteristic of substrate materials.

SUMMARY OF THE INVENTION

[0005] A small-sized multi-frequency antenna duplexer is presented. Theantenna duplexer uses plural antenna duplexers, each of which includestwo surface acoustic wave filters each for transmitter and receiverhaving passing bands different in frequency from each other, attenuatingother's passing band each other. This multi-frequency antenna duplexercontains plural antenna duplexers mounted in one package. Further thepassing band of each antenna duplexer is different from those of otherantennas.

[0006] Thus, the multi-frequency antenna duplexer is reduced in size.

[0007] In this multi-frequency antenna duplexer, a first piezoelectricsubstrate on which plural transmitter surface acoustic wave filters areformed, a second piezoelectric substrate on which plural receiversurface acoustic wave filters are formed, and a phase shift substratehaving a function of rotating the phase of each transmission band atleast in each receiver surface acoustic wave filter are mounted in onepackage. Thus, the multi-frequency antenna duplexer suppresses signalleak between transmission and reception portions, and is reduced in sizewhile maintaining isolation.

[0008] Further, in this multi-frequency antenna duplexer, transmittersurface acoustic wave filters and receiver surface acoustic wavefilters, which constitute the antenna duplexer having passing bandsdifferent in frequency, are formed individually on one piezoelectricsubstrate. Further in each receiver surface acoustic wave filter, phaseshift substrate having a function of rotating the phase of eachtransmission band are configured and mounted in a three-dimensionalstructure in one package. Thus, in this multi-frequency antennaduplexer, plural antenna duplexers, having passing bands largelydifferent in frequency from each other, can be reduced in size withoutdeteriorating the characteristics.

[0009] Herein, in the multi-frequency antenna duplexer, as for theantenna duplexer for two frequencies corresponding to two passing bandfrequencies, only one antenna output terminal may be required byconnecting a branching filter installed in the one package as theantenna duplexer to the antenna terminal of each antenna duplexer. As aresult, a small-sized multi-frequency antenna duplexer may be obtained.

[0010] Further, by forming the phase shift substrate and branchingfilter used in the multi-frequency antenna duplexer in the package innerlayer, an multi-frequency antenna duplexer of further smaller size isobtained.

[0011] Moreover, in the multi-frequency antenna duplexer, by using thesurface acoustic wave filters and bulk wave filters selectivelydepending on the passing band frequency or desired filtercharacteristic, an antenna duplexer for plural frequency having asuperior performance can be realized in a smaller size.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a perspective view of an multi-frequency antennaduplexer according to embodiment 1 of the invention.

[0013]FIG. 2 is a circuit diagram of the multi-frequency antennaduplexer according to embodiment 1.

[0014]FIG. 3 shows the frequency characteristics of the multi-frequencyantenna duplexer according to embodiment 1.

[0015]FIG. 4 is a perspective view of another multi-frequency antennaduplexer according to embodiment 1.

[0016]FIG. 5 is a circuit diagram of the another multi-frequency antennaduplexer according to embodiment 1.

[0017]FIG. 6 shows the frequency characteristics of the anothermulti-frequency antenna duplexer according to embodiment 1.

[0018]FIG. 7 is a perspective view of a different multi-frequencyantenna duplexer according to embodiment 1.

[0019]FIG. 8 is a circuit diagram of the different multi-frequencyantenna duplexer according to embodiment 1.

[0020]FIG. 9 shows the frequency characteristics of the differentmulti-frequency antenna duplexer according to embodiment 1.

[0021]FIG. 10 is a perspective view of the multi-frequency antennaduplexer incorporating a phase shift substrate according to embodiment1.

[0022]FIG. 11 is a perspective view of a multi-frequency antennaduplexer according to embodiment 2 of the invention.

[0023]FIG. 12 is a circuit diagram of the multi-frequency antennaduplexer according to embodiment 2.

[0024]FIG. 13 is a perspective view of a multi-frequency antennaduplexer in a prior art.

[0025]FIG. 14 is a circuit diagram of the multi-frequency antennaduplexer in the prior art.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] Preferred embodiments of the invention are described below whilereferring to FIG. 1 to FIG. 12. In FIG. 1 to FIG. 12, the same elementsare identified with the same reference numerals.

[0027] (Embodiment 1)

[0028]FIG. 1 is a perspective view of a multi-frequency antenna duplexeraccording to embodiment 1 of the invention. The multi-frequency antennaduplexer is formed of transmitter surface acoustic (SAW) filters 11 a,11 b, receiver SAW filters 12 a, 12 b, phase shift substrates 13 a, 13b, and a package 14 formed on a piezoelectric substrate. The phase shiftsubstrate rotates the phase of the input signal.

[0029] Herein, the phase shift substrate specifically rotates the phaseof the receiver SAW filters 12 a, 12 b in the transmission frequencyband of this antenna duplexer, and reduces the insertion loss in thepassing frequency band of the transmitter SAW filters. In other words,the phase shift substrate suppresses leak of signal between thetransmission side and reception side, and maintains the isolationbetween the two.

[0030] Outside of the package 14, there are antenna terminals 15 a, 15b, transmitter terminals 16 a, 16 b, receiver terminals 17 a, 17 b, andgrounding terminal (not shown), and connection pads 18 a to 18 f areprovided inside. Inside the package 14, the connection pads 18 a, 18 bare connected to transmitter terminals 16 a, 16 b, the connection pads18 c, 18 d to the receiver terminals 17 a, 17 b, and the connection pads18 e, 18 f to the antenna terminals 15 a, 15 b, respectively.

[0031] The transmitter SAW filters 11 a, 11 b, receiver SAW filters 12a, 12 b, and phase shift substrates 13 a, 13 b respectively have twoconnection terminals each. One terminal of the transmitter SAW filter 11a and connection pad 18 a are connected by a bonding wire 19 b, and oneterminal of the transmitter SAW filter 11 b and connection pad 18 b areconnected by a bonding wire 19 a. Another terminal of the transmitterSAW filter 11 a and connection pad 18 e are connected by a bonding wire19 c. Another terminal of the transmitter SAW filter 11 b and connectionpad 18 f are connected by a bonding wire 19 e. One terminal of thereceiver SAW filter 12 a and connection pad 18 c are connected by abonding wire 19 i, and one terminal of the receiver SAW filter 12 b andconnection pad 18 d are connected by a bonding wire 19 j. Anotherterminal of the receiver SAW filter 12 a and one terminal of the phaseshift substrate 13 a are connected by a bonding wire 19 g. Anotherterminal of the receiver SAW filter 12 b and one terminal of the phaseshift substrate 13 b are connected by a bonding wire 19 h. Anotherterminal of the phase shift substrate 13 a and connection pad 18 e areconnected by a bonding wire 19 d. Another terminal of the phase shiftsubstrate 13 b and connection pad 18 f are connected by a bonding wire19 f.

[0032]FIG. 2 is a circuit diagram of the multi-frequency antennaduplexer in FIG. 1.

[0033]FIG. 3 shows the frequency characteristics of the multi-frequencyantenna duplexer in FIG. 1. The antenna duplexer including transmitterSAW filter 11 a, receiver SAW filter 12 a, and phase shift substrate 13a respectively has passing characteristics 31 a, 32 a having passingbands 33 a, 34 a and attenuating bands 35 a, 36 a. In other words, thetransmitter filter and receiver filter mutually have attenuatingcharacteristics in other's passing band. The antenna duplexer includingtransmitter SAW filter 11 b, receiver SAW filter 12 b, and phase shiftsubstrate 13 b has passing characteristics 31 b, 32 b respectivelyhaving passing bands 33 b, 34 b and attenuating bands 35 b, 36 brespectively.

[0034] According to this configuration, since the transmitter SAWfilters 11 a, 11 b, receiver SAW filters 12 a, 12 b, and phase shiftsubstrates 13 a, 13 b can be mounted in one package 14, a small-sizedmulti-frequency antenna duplexer can be obtained.

[0035]FIG. 4 is a perspective view of another multi-frequency antennaduplexer according to embodiment 1. When passing frequency bands ofplural antenna duplexers are close to each other, the antenna duplexeris realized as shown in FIG. 4, by containing a transmitter SAW filter11 c having transmitter SAW filters 11 a, 11 b formed on onepiezoelectric substrate, a receiver SAW filter 12 c having receiver SAWfilters 12 a, 12 b formed on the one piezoelectric substrate, and aphase shift substrate 13 c on which plural phase shift circuits 13 a, 13b are formed. This antenna duplexer saves the mounting area in thepackage, and a further smaller antenna duplexer is obtained. Thethickness of the metal thin film on the piezoelectric substrate on whichthe SAW filter is formed preferably to be about 8 to 10% of thewavelength of the passing frequency obtained from the sonic velocity ofthe piezoelectric substrate.

[0036] Herein, since the passing frequency bands of the plural antennaduplexers are close to each other, plural SAW filters can be fabricatedin one process on the piezoelectric substrate.

[0037]FIG. 5 is a circuit diagram of another multi-frequency antennaduplexer in FIG. 4. FIG. 6 shows the characteristics of themulti-frequency antenna duplexer in FIG. 4 applied in a portabletelephone system.

[0038]FIG. 6 shows the characteristics in the Personal CommunicationSystem (PCS) in the United States. The passing band 33 a of thetransmitter SAW filter is 1850 MHz to 1885 MHz. The passing band 33 b ofthe transmitter SAW filter is 1885 MHz to 1910 MHz. The passing band 34a of the receiver SAW filter is 1930 MHz to 1965 MHz, and the passingband 34 b of the receiver SAW filter is 1965 MHz to 1990 MHz.

[0039]FIG. 7 is a perspective view of a further multi-frequency antennaduplexer according to embodiment 1. Contrary to the case above, when thepassing frequency bands of plural antenna duplexers are largelydifferent, the optimum value of thickness of the metal thin film on thepiezoelectric substrate is largely different between the plural antennaduplexers. Therefore, when these transmitter filters are formed on onepiezoelectric substrate, or when the respective receiver filters formedon the one piezoelectric substrate, it is difficult to optimize thethickness of the metal thin film.

[0040] Accordingly, as shown in FIG. 7, the transmitter SAW filter 11 aand receiver SAW filter 12 a of the one antenna duplexer closer to eachother in the service frequency band are formed on one piezoelectricsubstrate 20 a, while the transmitter SAW filter 11 b and receiver SAWfilter 12 b are formed on a piezoelectric substrate 20 b. As a result, asmall-sized antenna duplexer is obtained without deteriorating thecharacteristics. Thus, plural antenna duplexers having largely differentpassing band frequencies can be reduced in size without deterioratingthe characteristics.

[0041]FIG. 8 is a circuit diagram of the multi-frequency antennaduplexer in FIG. 7, and FIG. 9 shows the frequency characteristics ofthe multi-frequency antenna duplexer in FIG. 7 applied in a portabletelephone system.

[0042]FIG. 9 shows the characteristics in the dual band system in theglobal system for mobile communications/digital cellular system(GSM/DCS) in Europe. The passing band 33 a of the transmitter SAW filteris 880 MHz to 915 MHz, and the passing band 33 b of the transmitter SAWfilter is 1710 MHz to 1785 MHz. The passing band 34 a of the receiverSAW filter is 925 MHz to 960 MHz, and the passing band 34 b of thereceiver SAW filter is 1805 MHz to 1880 MHz.

[0043] To realize a further smaller multi-frequency antenna duplexer, asshown in FIG. 10, phase shift substrates 13 a, 13 b may be installed inthe inner layer of the package 14. One terminal of the receiver SAWfilter 12 a is connected to the connection pad 18 g in the package 14through wire bonding 19 g, and one terminal of the receiver SAW filter12 b is connected to the connection pad 18 h in the package 14 throughwire bonding 19 h. The connection pad 18 g and one end of a phase shiftline 21 a are connected by way of a through hole 22 a, and theconnection pad 18 h and one end of a phase shift line 21 b are connectedby way of a through hole 22 c. The connection pad 18 e and another endof the phase shift line 21 a are connected by way of a through hole 22b, and the connection pad 18 f and another end of the phase shift line21 b are connected by way of a through hole 22 d.

[0044] This circuit is the same as the one shown in FIG. 5. Since thephase shift line is incorporated in the inner layer in the package, themounting area of the phase shift substrate is curtailed, so that anmulti-frequency antenna duplexer of further smaller size is realized.

[0045] In other words, the phase shift substrates, and transmitter andreceiver SAW filters can be configured in a solid structure, so that afurther reduction in size is realized.

[0046] In embodiment 1, an antenna duplexer for two frequenciesdifferent in passing band is explained. An antenna duplexer for three ormore frequencies can be similarly mounted together in one package. Whenmounting the SAW filters and phase shift substrates in the package,instead of connecting them to the terminal of the package by wirebonding, by directly connecting them to the package with flip chips, afurther smaller antenna duplexer is obtained.

[0047] (Embodiment 2)

[0048]FIG. 11 is a perspective view of a multi-frequency antennaduplexer according to embodiment 2 of the invention, and FIG. 12 is itscircuit diagram.

[0049] In the multi-frequency antenna duplexer in FIG. 11, the sameelements as shown in FIG. 7 explained in embodiment 1 shown in FIG. 7,and corresponding components are identified with the same referencenumerals. A branching filter 23 is incorporated in the package 14.

[0050] As shown in FIG. 12, one terminal of the transmitter SAW filter11 a and one terminal of the branching filter 23 are connected to thephase shift substrate 13 a in one antenna duplexer by way of wirebondings 19 c, 19 d, respectively. One terminal of the transmitter SAWfilter 11 b and another terminal of the branching filter 23 areconnected to the phase shift substrate 13 b in another antenna duplexerby way of wire bondings 19 e, 19 f, respectively.

[0051] This antenna duplexer is applicable to dual band system such asthe global system for mobile communications/digital cellular system(GSM/DCS) explained in embodiment 1, while only one antenna terminal isneeded. Therefore, the antenna duplexer is connected to the antennawithout resort to any external elements. As a result, the device usingit can be reduced in size.

[0052] Above is the explanation when the passing frequencies of pluralantenna duplexers are largely different from each other as explained inFIG. 7 in embodiment 1. When the passing frequencies of pluralantenna-duplexers are close to each other, a branching filter isinserted between terminals 15 a and 15 b in FIG. 4 in embodiment 1, sothat only one antenna terminal is needed.

[0053] Or, when the branching filter 23 is installed in the inner layerin the package 14 like the phase shift lines 21 a, 21 b in FIG. 10 inembodiment 1, a further smaller antenna duplexer is obtained. Herein,the phase shift lines, branching filter, and transmitter and receiverSAW filters can be configured in a three-dimensional structure, so thata further reduction in size is realized.

[0054] In embodiments 1 and 2, when the passing band frequency isextremely low or depending on the desired filter characteristics, bulkwave filters may be used instead of the SAW filters. In the bulk wavefilter, the piezoelectric substrate itself vibrates mechanically,thereby forming a resonator. Unlike the SAW filters, the bulk wavefilters needs to be installed in a hollow structure of piezoelectricsubstrate. However, in the antenna duplexer of the invention, it iseasily realized by changing the shape of the package. Thus, two types offilters can be used selectively depending on the passing band frequencyand filter characteristics, so that the size can be reduced whilemaintaining the performance.

[0055] Industrial Applicability

[0056] According to the invention, as described herein, being formed oftwo SAW filters each for transmission and reception having passing bandsdifferent in frequency, a small-sized antenna duplexer for pluralfrequencies can be obtained by using a plurality of antenna duplexersfor mutually attenuating the other's passing band each other.

[0057] In an antenna duplexer mounting two antenna duplexers and abranching filter in one package, the branching filter connectsrespective antenna terminals thereof. Thus, the antenna duplexerrequires only one antenna output terminal. As a result, themulti-frequency antenna duplexer itself can be reduced in size. At thesame time, it is not necessary to attach external element to the antennaterminal, and the device for using it is reduced in size.

[0058] Further, by incorporating the phase shift substrates andbranching filter in the inner layer in the package, the mounting area ofelements in the package is curtailed. Therefore, a smallermulti-frequency antenna duplexer is realized.

[0059] By using bulk wave filters in the transmitter and receiverfilters depending on the passing band frequency or desired filtercharacteristic, a small-sized multi-frequency antenna duplexer ofsuperior performance may be realized. Reference numerals in the drawings11a, 11b, 11c Transmitter surface acoustic wave filter 12a, 12b, 12cReceiver surface acoustic wave filter 13a, 13b, 13c, 13d Phase shiftsubstrate 14 Package 15a, 15b, 15c, 15d Antenna terminal 16a, 16b, 16c,16d Transmitter terminal 17a, 17b, 17c, 17d Receiver terminal 18a-18hConnection pad 19a-19k Bonding wire 20a, 20b Piezpelectric substrate21a, 21b Phase shift line 22a-22d Through hole 23 Branching filter 24Substrate 25a, 25b Receiver coaxial filter 26a, 26b Transmitter coaxialfilter 27a, 27b Single Pole Double Throw Switch

1. A multi-frequency antenna duplexer comprising: a package, and aplurality of antenna duplexers, mounted in said package, havingdifferent passing bands from each other, wherein each of said pluralityof antenna duplexers includes a transmitter surface acoustic wave (SAW)filter and a receiver SAW filter having a passing band different fromthe passing band of the transmitter SAW filter, the transmitter SAWfilter of said each of the plurality of antenna duplexers is formed on afirst piezoelectric substrate, and the receiver SAW filter of said eachof the plurality of antenna duplexers is formed on a secondpiezoelectric substrate.
 2. The multi-frequency antenna duplexer ofclaim 1, wherein in each of the receiver SAW filters, a phase shiftsubstrate for rotating a phase of a transmission band of saidmulti-frequency antenna duplexer including said each of the receiver SAWfilters is incorporated between the first piezoelectric substrate andthe second piezoelectric substrate in the package.
 3. Themulti-frequency antenna duplexer of claim 2, wherein at least first andsecond transmitter SAW filters are formed on the first piezoelectricsubstrate, at least first and second receiver SAW filters are formed onthe second piezoelectric substrate, the first transmitter SAW filter andthe first receiver SAW filter are disposed nearly adjacent to each otherby way of the phase shift substrate, and the second transmitter SAWfilter and the second receiver SAW filter are disposed nearly adjacentto each other by way of the phase shift substrate.
 4. Themulti-frequency antenna duplexer of claim 2, wherein the phase shiftsubstrate is formed in an inner layer of the package.
 5. Anmulti-frequency antenna duplexer comprising: a package, and a pluralityof antenna duplexers, mounted in said package, having different passingbands from each other, wherein each of said plurality of antennaduplexers includes a transmitter filter and a receiver filter having apassing band different from a passing band of the transmitter filter, atleast one of the transmitter filter and the receiver filter is a bulkwave filter, and when one of the transmitter filter and the receiverfilter is the bulk wave filter, another is a surface acoustic wave (SAW)filter.
 6. The multi-frequency antenna duplexer of claim 5, wherein thereceiver filter of any one of the plurality of antenna duplexers is theSAW filter, in the SAW filter, a phase shift substrate for rotating aphase of a transmission band of the antenna duplexer including the SAWfilter is incorporated in the package.
 7. The multi-frequency antennaduplexer of claim 6, wherein the phase shift substrate is formed in aninner layer of the package.
 8. A multi-frequency antenna duplexercomprising: a package, two antenna duplexers, mounted in said packagehaving, different passing bands from each other, and a branching filterfor coupling antenna terminals of the two antenna duplexers and oneantenna terminal included in the package, wherein each of said twoantenna duplexers includes a transmitter surface acoustic wave (SAW)filter and a receiver SAW filter having a passing band different from apassing band of the transmitter SAW filter, the transmitter SAW filterof each of the two antenna duplexers is formed on a first piezoelectricsubstrate, and the receiver SAW filter of each of the two antennaduplexers is formed on a second piezoelectric substrate.
 9. Themulti-frequency antenna duplexer of claim 8, wherein in each of thereceiver SAW filters, a phase shift substrate for rotating a phase of atransmission band of said multi-frequency antenna duplexer includingsaid each of the receiver SAW filter is incorporated between the firstpiezoelectric substrate and the second piezoelectric substrate in thepackage.
 10. The multi-frequency antenna duplexer of claim 9, wherein atleast first and second transmitter SAW filters are formed on the firstpiezoelectric substrate, at least first and second receiver SAW filtersare formed on the second piezoelectric substrate, the first transmitterSAW filter and the first receiver SAW filter are disposed nearlyadjacent to each other by way of the phase shift substrate, and thesecond transmitter SAW filter and the second receiver SAW filter aredisposed nearly adjacent to each other by way of the phase shiftsubstrate.
 11. The multi-frequency antenna duplexer of claim 9, whereinthe phase shift substrate and the branching filter are formed in aninner layer of the package.
 12. A multi-frequency antenna duplexercomprising: a package, two antenna duplexers, mounted in said package,having different passing bands each other, and a branching filter forcoupling antenna terminals of the two antenna duplexers and one antennaterminal included in the package, wherein each of said two antennaduplexers includes a transmitter filter and a receiver filter having apassing band different from a passing band of the transmitter filter, atleast one of the transmitter filter and the receiver filter is a bulkwave filter, and when one of the transmitter filter and the receiverfilter is the bulk wave filter, another is a surface acoustic wave (SAW)filter.
 13. The multi-frequency antenna duplexer of claim 12, whereinthe receiver filter is the SAW filter, in the SAW filter, a phase shiftsubstrate for rotating a phase of transmission band of the antennaduplexer including the SAW filter is incorporated in the package. 14.The multi-frequency antenna duplexer of claim 13, wherein the phaseshift substrate and the branching filter are formed in an inner layer ofthe package.